With key in "on" position, use a test light or voltmeter to see if you have voltage entering the switch, and when the brake pedal is pressed down that voltage is leaving the switch. If no voltage to the switch, check fuses and wiring.

I have a Mazda 626 Auto hatchback 1990/91 my brake lights have stop working and dont know why i have check All fuses the brake pedel switch had to be replaced checked all the bulbs but still nothin anyone got any ideas at all